In nuclear power installations, process components can be exchanged and repair work on such components can only be performed by remote handling because of the radioactive hazard. Such work is conducted by using television cameras and monitors together with mobile remote-handling apparatus. At the same time, also cable-operated cranes or other lifting equipment are used by which tools, working stock and exchange parts or entire process components are accurately positioned.
Lifting tackle or hoists with load-bearing hooks are used for transporting relatively large or heavy process components. On the other hand, working stock, such as impact wrenches or manipulators are moved by hoists to the appropriate working station in the shielded cell intended to hold the process components. Therefore, several hoists have to be provided for the various items or alternatively, changing the processing component or tool on a hoist has to be undertaken in a complicated process. Changing is time-consuming and difficult because it is only possible under remote-handling conditions.
Published German patent application, DE-OS No. 34 33 311 discloses a tool-changing device used in the related technical field of industrial robots and manipulators. In this field, in contrast to hoists such as a crane, other handling conditions have to be observed The known tool-changing device for industrial robots comprises an upper part which remains on the industrial robot. The associated lower part is mounted on the relevant tool When a tool has to be changed, the tool is placed in a device magazine and exchanged, together with the lower part, for a different lower part on which a different tool is mounted. A linear drive unit disposed in the upper part guides a hook-shaped structure along a slide until it engages a matching member disposed in the relevant lower part. The linear drive unit can be constructed as a compressed air cylinder, a hydraulic cylinder or an electrically operated linear drive.
Nuclear facilities such as plants for reprocessing irradiated nuclear fuels comprise what are referred to as "large-area shielded cells" in which the process components are set up on racks or frames. However, the device described above is unsuitable in such facilities since it requires a very accurate longitudinal and non-rotatable guidance of the upper part in relation to the lower part. This need for accurate guidance hampers remote-handling ability. Furthermore, in such plants, drive units which operate on compressed air or hydraulics are avoided.